One for Claude Code and Cowork

Connect Claude Code and Claude Cowork to 700+ apps (Gmail, Slack, Shopify, HubSpot, Stripe, Notion, Linear, Salesforce, QuickBooks, Google Calendar, and more) through One's remote MCP server.

Four tools. Real API documentation for 80,000+ actions. OAuth sign-in in your browser. Nothing to install and no API keys to manage: One handles every platform's auth server-side.

Learn more about the server this plugin connects to: https://www.withone.ai/products/mcp

Discover -> Search -> Read the docs -> Execute
list_one_integrations -> search_one_platform_actions -> get_one_action_knowledge -> execute_one_action

What you can do

• "Send an email to alex@acme.com with the Q3 summary" (Gmail)
• "Post 'deploy is live' to #engineering" (Slack)
• "Create a Stripe customer for this signup" (Stripe)
• "List my open Linear issues" (Linear)
• "Write a Next.js route that creates a HubSpot contact" (Claude writes code from the live API schema)

Install

Claude Code

/plugin marketplace add withoneai/claude-plugin
/plugin install one@one

Once approved in Anthropic's community marketplace, you will also be able to run /plugin marketplace add anthropics/claude-plugins-community then /plugin install one@claude-community.

Then sign in:

/mcp

Pick One, then Authenticate. Your browser opens One's consent screen, where you choose which connections this Claude Code client may use, whether it can write or only read, and whether to enable knowledge-only mode. That's it. Tokens are stored securely and refreshed automatically.

Or from your shell: claude mcp login plugin:one:one.

Claude Cowork

In the Claude desktop app, open Customize, then Plugins, choose Add marketplace, and enter withoneai/claude-plugin. Install One from that marketplace. When prompted, sign in to One in your browser and scope access on the consent screen. The plugin registers the One connector and both skills for you; the skills appear under the + menu, Plugins, One.

Prerequisites

• A One account with the apps you want to use connected: app.withone.ai.
• Claude Code v2.1.196 or later (for the OAuth scope handling the server relies on).

Usage

Just ask. The bundled skills teach Claude the discover, search, read, execute funnel, so you don't have to name tools:

Skill	When Claude uses it
/one:integrations	Doing things in apps: send, create, update, look up, sync.
/one:integration-code	Writing code that calls a third-party API, using the real schema instead of a guessed one.

execute_one_action performs a live call (sending email, creating records, and so on), so Claude Code asks you to approve it. The three discovery tools are read-only.

Tools

Tool	What it does
list_one_integrations	Your connected accounts, each with its connection key and the access it allows.
search_one_platform_actions	Find actions on a platform from a natural-language query.
get_one_action_knowledge	An action's full documentation: parameters, types, request/response shape, gotchas.
execute_one_action	Perform the live API call through One.

Tool names inside Claude Code are prefixed mcp__plugin_one_one__ (for example mcp__plugin_one_one__execute_one_action). Use those in permission rules or hooks.

Scoping and safety

Access is decided on One's OAuth consent screen when you authenticate, not in a config file:

On the consent screen	Effect
Which connections	Only the selected accounts appear in list_one_integrations.
Read / full / specific actions per connection	Reflected in each connection's access field; disallowed calls are refused server-side.
Knowledge-only mode	Removes execute_one_action entirely. Claude can read every API's real schema and write code, but can never perform a live operation.

To change scoping later: /mcp, select One, choose Clear authentication, then authenticate again.

Every third-party call is proxied by One, so no platform tokens ever touch your machine.

How it works

The plugin's .mcp.json points Claude Code at One's Streamable-HTTP MCP endpoint (https://mcp.withone.ai/mcp). Claude Code discovers the OAuth server via RFC 9728 protected-resource metadata, registers itself dynamically (RFC 7591), and runs a PKCE authorization-code flow in your browser. Nothing runs locally.

Troubleshooting

• Tools don't appear / "needs authentication": run /mcp, select One, and authenticate.
• execute_one_action is missing: you chose knowledge-only mode on the consent screen. Clear authentication in /mcp and sign in again with execution enabled.
• A platform isn't listed: it's not connected (or wasn't selected on the consent screen). Connect it at app.withone.ai, or re-authenticate to widen the scope.
• "Missing required OAuth scope": re-authenticate via /mcp.
• You also use the One connector on claude.ai: Claude Code deduplicates servers by endpoint, so a session shows either plugin:one:one or claude.ai One (same server, same four tools). If the connector wins, tool names appear as mcp__claude_ai_One__* instead. Everything else is identical.
• Working on this repo itself: its .mcp.json doubles as a project-scoped server when you open Claude Code here. Add "disabledMcpjsonServers": ["one"] to .claude/settings.local.json to avoid a duplicate alongside --plugin-dir.

Links

• One: https://www.withone.ai
• One's remote MCP server: https://www.withone.ai/products/mcp
• MCP docs: https://www.withone.ai/docs/mcp
• Dashboard: https://app.withone.ai
• This plugin: https://github.com/withoneai/claude-plugin

License

MIT. See LICENSE.